Magnetic structures



A ril 4, 1967 J. W. ROE

MAGNETIC STRUCTURES Filed Oct. 19, 1965 INVENTOR d/ivwfs M 01:

J/M A ORN Y United States Patent Ofiiice 3,312,132 Patented Apr. 4, 1967 3,312,132 MAGNETIC STRUCTURES James W. Roe, Willowdale, Ontario, Canada, assignor to Basic Products Corporation, Milwaukee, Wis., a corporation of Wisconsin Filed Oct. 19, 1965, Ser. No. 498,017 4 Claims. (Cl. 8332) This invention relates to magnetic core structures for electrical induction apparatus such as transformers, reactors and the like, and especially to laminated magnetic core structures in which a stack of thin sheets, or laminations, of magnetic material is built up to form the core.

There are many forms of laminated core structure for transformers and reactors, one of which is known in the trade as a T and L type of lamination. Prior known T and L type laminations for transformer cores made in the same operation required the window height or width (the space between the leg of the T and the leg of each of the L-shaped portions) to be no more than one half of the width of the leg of the T portion if minimum scrap is desired.

The width of the leg of the T portion of the lamination times the stack height determines the amount of iron for the center core, and the width and height of the window on each side thereof determines the maximum number of turns of wire that can be provided on the legs of the core.

The principal object of the present invention is to provide a laminated core construction for reactors and transfiormers which embodies the use of T and L sections, and wherein the window height can be substantially increased over that of prior known T and L section trans former cores produced in the same operation.

Another object of the invention is to provide such a core in which two sets of laminations can be punched from a length of strip material normally used to punch the element for one set.

Still another object of the invention is to provide a method of punching laminations for T and L type transformer cores of such material so that a minimum of the strip material is lost in each punching.

In one aspect of the invention, a transformer or reactor core made in accordance with the principles of this invention may comprise a T-shaped section and two L-shaped sections in which the short legs of the L sections are aligned with respect to each other, and their length combined with that of the width of the central leg of the T section equals the length of the right angular leg of the T section plus the width of the long legs of the L section.

In another aspect of the invention, two sets of laminations can be punched simultaneously from the same length of strip material necessary to punch a single set of laminations.

In still another aspect of the invention, a die may be provided that will punch four of the L-shaped portions from a single length of strip material, and in which two pairs of T sections are arranged in nested and opposed relation.

In a further aspect of the invention, the punch die may produce the two T sections with their long legs in contact with each other, and with their right angular portions opposed to each other, the entire assemblage consuming a maximum of the area of a portion of the strip of a length equal to the sum of the length of a long leg of an L-shaped segment, the width of one of the L-shaped legs and the width of one of the cross members of the T.

In a still further aspect of the invention, diagonally opposed, nested L sections may be coextensive of the sheet of material from which they are to be punched and separated laterally to receive the opposed T sections with the long legs of the latter in contact with each other.

It has been found that designing a die capable of punching the T and L sections as above described consumes a minimum of strip material from which they are to be punched.

The above, other objects and novel features of the invention will 'become apparent from the following specification and accompanying drawing which are merely exemplary.

In the drawing:

FIG. 1 is a plan view of a strip of material from which the T and L sections have been punched and which are still arranged at the end of the strip material in their relation to each other as punched;

FIG. 2 is -a view of one of the laminations assembled for use as a transformer core;

FIG. 3 is an enlarged view of a portion of the strip of material shown in FIG. 1 from which the T and L sections have been punched; and

FIG. 4 is similar to FIG. 1 except that the strip width is in a different direction.

Referring to FIG. 2, the principles of the invention are shown as applied to a lamination of a transformer or reactor core comprising a T section 11 that includes a long center leg 12 and a right angular leg 13. The center leg 12 is adapted to comprise the center leg of the transformer core 10. Identical, opposed L sections may be combined with the T section 11 to complete a single lamination of the core 10. The one long leg 14 of the one L-shaped portion 15 may contact the one end of the leg '13 of the T section 11, and the free end of the short leg 16 of the L-shaped portion 15 may contact the side of the center leg 12 of the T section 11.

Another L-shaped section 17 may include an elongated leg portion 18 that contacts the opposite end of the leg 13 of the T section 11, while its short leg 19 contacts the side of the center leg 12 of the T section 11. There may be provided holes 20, 21, 22, 23, 24 and 25 in the T- and L-shaped sections for assembly purposes. Apparatus (not shown) may be provided in the long leg 12 of the T section 11 to provide various magnetic characteristics.

The next adjacent lamination for the core 10 may comprise elements identical With those just described, but they may be reversed. That is to say, the short leg section 13 of the T section 11 may overlap the joint be tween the short legs 16 and 19 of the L sections 15 and 17 and the side of the center leg 12 of the T section 11; and the continuous material between the short and long legs of the L sections may overlap the joints between the long legs of the L sections and the ends of the short leg of the T section 11. The holes 20 to 25, inclusive, of all sections will line up with the alternate disposition of the separate laminations so that bolts passing through a stack of these alternately arranged laminations form a core for a reactor or transformer. Instead of bolting, the core may be made secure by clamping or welding. Also the core may be composed of a stack of laminations not reversed.

Referring to FIG. 1, a strip of suitable metal 26 may have a width that is slightly greater than the summation of the length of the short leg of the T section 13 and the one short leg 16 of the L section 15.

It has been found that by designing a die so that the T sections 11 are arranged in the manner shown with the L sections on opposite sides thereof as illustrated, a mini mum length will be consumed in punching two sets of laminations for the core 10. The only material that is lost in the punching operation comprises the relatively small portions 27, 28, 29 and 30.

Referring to FIG. 3, the die is form d so as to produce two sets of laminations in the same operation. Thus, the T-shaped components are disposed in opposed relation with one edge of their long legs 12 in contact. The L- shaped components are nested in pairs and disposed diagonally oppositely. In this way, a minimum or" strip material is consumed.

In FIG. 4, the strip Ell moves from left to right but the dies are turned at right angles to that shown in FIG. 1. The punching operation then is carried out in a similar manner to that described above.

Although the various features of the improved method of punching lamination components for transformer and reactor cores have been shown and described in detail to fully disclose one embodiment of the invention, it will be evident that changes may be made in such deta ls and certain features may be used without others without departing from the principles of the invention.

The embodiments of the invention in which an eX- clusive property or privilege is claimed are defined as follows:

1. The method of making laminations for a transformer core and the like in which the components of each of laminations comprise a T-shaped component and two L-shaped components, which method comprises punching the components for two sets of laminations in the same operation from a piece of strip material having a width equal to twice the width of the long legs of the T plus four times the width of the L-shaped components, and of a length equal to the sum of the length of a T- shaped component plus twice the width of a short leg of an L-shaped component.

2. The method of making laminations for a transformer core and the like in which the components of each set of laminations comprise a T-shaped component and two L-shaped components, which method comprises puncin g the components for two sets of laminations in the same operation from a piece of strip material with the T-shaped components in opposed relation and one edge of their ll. long legs in contact, and the L-shaped components nested and arranged in opposed relation diagonally of the piece of strip material.

3. The method of making laminations for a transformer core and the like in which the components of each set of laminations comprise a T-shaped component and two L- shaped components, which method comprises punching the components for two sets of laminations in the same operation from a piece of strip material with the T-shaped components in opposed relation and one edge of their long legs in contact, the L-shaped components nested and disposed diagonally of said strip, with one edge of their long legs in contact and another edge of one of the L- shaped components in contact with one edge of the long legs of said T-shaped components.

The method of making laminations for a transformer core and the like in which the components of each set of laminations comprise a T-shaped component and two L-shaped components, which method comprises punching the components for two sets of laminations in the same operation from a piece of strip material with the TShapcd components in opposed relation and one edge of their long legs in contact, the L-shaped components nested and disposed diagonally of said strip, with one edge of their long legs in contact and another edge of one of the L- shaped components in contact with one edge of the long legs of said T-shaped components, and with the end of the short leg of the outermost nested L-shaped component in contact withv one end of the short leg of one of said T-s'naped components.

References Cited by the Examiner UNITED STATES PATENTS 3,153,961 10/1964 Feinberg et al 83--5O WILLIAM W. DYER, JR., Primary Examiner.

I M. MEISTER, Assistant Examiner. 

2. THE METHOD OF MAKING LAMINATIONS FOR A TRANSFORMER CORE AND THE LIKE IN WHICH THE COMPONENTS OF EACH SET OF LAMINATIONS COMPRISE A T-SHAPED COMPONENT AND TWO L-SHAPED COMPONENTS, WHICH METHOD COMPRISES PUNCHING THE COMPONENTS FOR TWO SETS OF LAMINATIONS IN THE SAME OPERATION FROM A PIECE OF STRIP MATERIAL WITH THE T-SHAPED 